Nano-fabrication involves the fabrication of very small structures, e.g., having features on the order of nanometers or smaller. One area in which nano-fabrication has had a sizeable impact is in the processing of integrated circuits. As the semiconductor processing industry continues to strive for larger production yields while increasing the circuits per unit area formed on a substrate, nano-fabrication becomes increasingly important. Nano-fabrication provides greater process control while allowing increased reduction of the minimum feature dimension of the structures formed. Other areas of development in which nano-fabrication has been employed include biotechnology, optical technology, mechanical systems and the like.
An exemplary nano-fabrication technique is commonly referred to as imprint lithography. Exemplary imprint lithography processes are described in detail in numerous publications, such as U.S. Patent Application Publication No. 20040065976 to Sreenivasan et al., entitled “Method and a Mold to Arrange Features on a Substrate to Replicate Features having Minimal Dimensional Variability;” U.S. Patent Application Publication No. 20040065252 to Sreenivasan et al., entitled “Method of Forming a Layer on a Substrate to Facilitate Fabrication of Metrology Standards;” and U.S. Pat. No. 6,936,194 to Watts, entitled “Functional Patterning Material for Imprint Lithography Processes;” all of which are incorporated by reference herein.
The fundamental imprint lithography technique disclosed in each of the aforementioned United States patent application publications and United States patent includes formation of a relief pattern in a polymerizable layer and transferring a pattern corresponding to the relief pattern into an underlying substrate. The substrate may be positioned upon a motion stage to obtain a desired position to facilitate patterning thereof. A template is employed spaced-apart from the substrate with a formable liquid present between the template and the substrate. The liquid is solidified to form a solidified layer that has a pattern recorded therein that is conforming to a shape of the surface of the template in contact with the liquid. The template is then separated from the solidified layer such that the template and the substrate are spaced-apart. The substrate and the solidified layer are then subjected to processes to transfer, into the substrate, a relief image that corresponds to the pattern in the solidified layer.
Referring to FIG. 1, the basic concept behind imprint lithography is forming a relief pattern on a substrate that may function as, inter alia, an etching mask so that a pattern may be formed into the substrate that corresponds to the relief pattern. A system 10 employed to form the relief pattern includes a stage 11 upon which a substrate 12 is supported, and a template 14 having a mold 16 with a patterning surface 18 thereon. Patterning surface 18 may be substantially smooth and/or planar, or may be patterned so that one or more recesses are formed therein. Template 14 is coupled to an imprint head 20 to facilitate movement of template 14. A fluid dispense system 22 is coupled to be selectively placed in fluid communication with substrate 12 so as to deposit polymerizable material 24 thereon. A source 26 of energy 28 is coupled to direct energy 28 along a path 30. Imprint head 20 and stage 11 are configured to arrange mold 16 and substrate 12, respectively, to be in superimposition, and disposed in path 30. Either imprint head 20, stage 11, or both vary a distance between mold 16 and substrate 12 to define a desired volume therebetween that is filled by polymerizable material 24.
Typically, polymerizable material 24 is disposed upon substrate 12 before the desired volume is defined between mold 16 and substrate 12. However, polymerizable material 24 may fill the volume after the desired volume has been obtained. After the desired volume is filled with polymerizable material 24, source 26 produces energy 28, which causes polymerizable material 24 to solidify and/or cross-link, forming polymeric material conforming to the shape of the substrate surface 25 and mold surface 18. Control of this process is regulated by processor 32 that is in data communication with stage 11 imprint head 20, fluid dispense system 22, and source 26, operating on a computer-readable program stored in memory 34.
One criterion associated with accurately transforming a pattern into a polymerizable material is to reduce, if not prevent, adhesion to the template of the solidified layer, while ensuring suitable adhesion to the substrate. This is referred to as preferential release and adhesion properties. By preferential release and adhesion, the pattern recorded in the solidified layer is not distorted during separation of the template.
A method to improve the adhesion of the solidified layer to the substrate is to introduce an adhesion primer layer (or primer layer). The adhesion primer layer needs to adhere well to both the solidified layer and the substrate. Currently, the adhesion primer layer is put down by a spin coating method. After one side is coated, the wafer is flipped and the coated side physically touches part of spin coating apparatus in order to coat the second side. The physical contact between the spin coating apparatus and the coated surface can result in particle contamination of the adhesion primer layer. In addition, utilizing the spin coating process to apply the adhesion primer layer may limit the overall throughput of the process.